Aircraft drift angle indicator



Aug. 9, 1949. R. FREAs AIRCRAFT DRIFT ANGLE 'INDICATOR 3 Sheets-Sheet 1Filed Dec. 6, 1944 .1 ASS m Aug. 9, 1949. R. l.. FREAs 2,478,866

AIRCRAFT DRIFT ANGLE INDICATOR Filed Dec. 6, 1944 3 Sheets-Sheet 2 Aug.9, 1949. R. FREAS 2,478,866

AIRCRAFT DRIFT ANGLE INDICATOR I Filed Deo. e, 1944 s sheets-sheet 3 2 659 I I ll Safety Pas/'flan Elecfr'ica/ I l SWI'CI Ffg. 6

:05 Pressure Switch Transmitter I nvenfar Raymond l.. Freas AttorneyPatented Aug. 9, i949 UNIi its

(Granted under the act of March 8, 1883, as amended April 30, 1928; 370O. G. 757) Claims.

This invention relates to an improved radio transmitting apparatus forquickly and accurately determining the drift factor in aerial navigationand more particularly to an improved apparatus which maybe dropped orlaunched from an aircraft or other mobile object in any manner to awater surface or a land surface, and which automatically radiates radiofrequency signals while resting on the aforementioned water surface orland surface. The invention further relates to improved means forcontrolling the descent of said apparatus through the atmosphere afterbeing dropped or launched from an aircraft, and to means forautomatically initiating the proper operation of said apparatus whendropped or launched from the aircraft or other mobile object to a watersurface or land surface.

An object of the invention when used in conjunction with any radioreceiver or radio direction nder is to provide a means for determiningthe drift and actual direction of motion of an aircraft or other mobileobject relative to the adjacent surface.

A further object of the invention when used in conjunction with anyradio receiver or radio direction finder is toprovide a means for themarking of any object or position on a water surface or land surface sothat a homing course to the object or position may be set.

Another object is to provide an improvement wherein a safety electricswitch forms a part of the invention, said safety electric switch beingsecurely held in an open position to prevent accidental discharge of acharge of explosive powder prior to launching the apparatus andremaining in an operative state for the purpose of closing 'an electricpowder charge firing circuit and which will not be adversely affected bysurrounding atmospheric or liquid pressures.

Another object is to provide an improvement wherein a time delayposition operated electric switch contains a time delay feature andcloses an electric powder charge firing circuit upon the expiration ofthe time delay and completion of certain other operations, both inatmosphre and water.

Another object is to provide an improvement wherein a multi-sectioncollapsible tubular teescopic antenna is centrally and securelycontained within the apparatus before the apparatus assumes an operablestate, and which is extended or erected in a secure manner after theapparatus assumes an operable state by the generation of gas pressurecaused by a timed explosive powder charge.

Another object is to provide an antenna lock and release cylinder forlocking and automatically releasing the lock of an antenna containedwithin an object to be launched or dropped from an aircraft or othermobile object to a surface of the earth.

Another object is to provide a pressure operated electric switchactuated by the antenna erecting gas pressure for the purpose of closingradio transmitting circuits.

Another objectI is the provision of a device which will be economical tomanufacture, reliable in operation and which possesses all the qualitiesof ruggedness and dependability in service.

A brief description of the figures of the drawing are as follows:

Fig. 1 is an elevation partly in section of the v Fig. 7 is a wiringdiagram of the transmitter circuit.

Fig. 8 is a magnied sh if of Fig. 5.

One form of the invention is illustrated in the above figures. This formof the invention is primarily a compact radio transmitter which,together with its internally contained telescoping powder operatedantenna, safety electric switch, and time delayposition operated switch.is designed so that it can be dropped from an aircraft to a watersurface and remain in an operative state for the purpose of radiatingradio frequency' signals while on the water surface. A detaileddescription of the radio transmitter vwill not be given since any one ofa variety of simple transmitter circuits may be used suc- 1ciessfullywith the apparatus of the present inven- The operation of the inventionis briey described as follows: The apparatus is dropped from anaircraft, and after falling freely for a predetermined time or to apredetermined altitude, a'

timing device or an altimeter controls theV automatic release of anelectric safety switch, a mercury switch, and a parachute which issecurely attached to one end of the device.

The parachute thus serves a dual purpose; first, to automaticallyrelease the counterweight from the apparatus by inertia reaction and,second, to lower the apparatus to the water or land surface. The purposeof the counterweight isl to x the center of gravity of the apparatus in`such a manner that desirable orientation in free flight isaccomplished. The center of gravity and center of buoyancy of theapparatusare such that, upon alighting on the water surface, theapparatus assumes an inverted position with respect to that which it hadwhile falling through the atmosphere.

A mercury switch utilizing a time delay feature closes the ring circuitafter the apparatus has assumed operating position in the water. Thefiring circuit ignites a powder charge for the purpose of generating agas pressure for erecting a telescopic antenna and closing apressure-operated electric switch which starts operation of the radioand causes radio frequency signals to be radiated.

The pictorial sketches in Fig. 4 illustrate in (C), the apparatus justafter release from the aircraft, (B), just after release of theparachute, and (A), its operating position in the water.

The following paragraphs give a more detailed description of theapparatus.

Referring to Fig. 4, the apparatus C, is composed of an assembly of thedevices of Fig. 1, Fig. 2, Fig. 3, Fig. 5 and a parachute. The device ofFig. 3 is securely attached in a detachable manner to Fig. 2 by means ofthe inside diameter of casing |43 engaging the smaller diameter ofbulkhead 29.

Prior to launching the apparatus from-the aircraft, the timing device oraltimeter |44is adjusted to a predetermined time or altitude which isdependent upon the altitude of the aircraft. At the instant of lauchingthe timing device or altimeter |44 is manually set in an operative stateso that it counts time or altitude While the apparatus is freely fallingas shown in C of Fig. 4. During the time the apparatus is freely fallingas shown in C of Fig. 4, the parachute'shown in B of Fig. 4, is securelyretained within the compartment bounded by bulkheads of |49, |48,y |46and longitudinally split inner casing |41. Longitudinally split innercasing |52 is supported in positionv by the smaller diameter of bulkhead29 and is retained in a fixed angular position relative to bulkhead 29for the purpose of locating bulkhead |49, spring retainer |5|, andspring 2 relative to cap 3. Spring retainer |5l is securely attached tobulkhead |49. The rectangular opening in bulkhead |49 permits passage ofthe parachute shroud lines from ring 33, where they are securelyattached, to within the compartment bounded by bulkheads |49, |48, |46and longitudinally split inner casing 41. The timing device or altimeter|44 is securely attached to outer casing |43 and forms a retainer bywhich gas check collar |45, bulkhead |46, longitudinally split innercasing |41, bulkheads |48 and |49, spring retainer |52, and spring 2,are all confined in their respective positions Within outer casing |43and relative to bulkhead 29. Fins |4| are securely attached to iinsupports |42 and |53 which are securely attached to outer casing |43 andprovide a means of directing the flight when the invention is freelyfalling as shown in C of Fig. 4. Safety switch lanyard |3| is securelyattached to fin support |53. Spring 2 overpowers spring` 4 when Fig. 3is assembled to Fig. 2 so that mercury is not permitted to enter cavityl5 of the time delay position operated switch of which a more completeexplanation will later be made.

During the time the apparatus is freely falling in a state as shown in Cof Fig. 4, the timing device or altimeter |44 counts time or altitude,and at the expiration of the preset time or altitude causes the ignitionof a charge of explosive powder contained within the space bounded bytimer |44, gas check collar |45, and bulkhead |46 for the purpose offorcibly separating and freeing Fig. 3 from Fig. 2. A detaileddescription of the manner in which Fig. 3 is separated from Fig. 2 is:the gas pressure generated by ignition of the powder charge expands inthe volume bounded by timer |44, gas check collar |45 and bulkhead |48thus separating timer |44, outer casing |43, iins |4I, fm bands |42 and|53, and lanyard |3|, all of which are securely attached together, frombulkhead 29 of Fig. 2 by means of a telescopic action of a casing |43about longitudinally split inner casing |52, bulkheads |49 and |48,longitudinally split inner casing |41 and bulkhead |46; in addition toother purposes herein noted, bulkhead |46 provides a means upon whichthe back pressure of the exploded powder charge reacts since it issupported by longitudinally split l inner casing |41, bulkheads |49 and|48, and longitudinally split inner casing |52 all of which aresupported by bulkhead 29 and confined in a slidable manner within outercasing |43; further, gas check collar |45, bulkhead |46 andlongitudinally split inner casing |41, and bulkheads |48 and |49 providea means of protecting the parachute from flames or hot gases resultingfrom the powder explosion and also provide a means of protecting theparachute mechanically at all times during free flight of the apparatusand more especially provide a means of protecting the parachute frombecoming damaged during the ejection of outer casing |43.

In the interval of operation of the invention between that shown by Cand B of Fig. 4. the outer casing |43 with all parts previously identiedherein as being attached securely thereto including keeper |36-of safetyswitch -2, gas check collar I 45, 4bulkhead |46, longitudinally splitinner casing |41, bulkheads |49 and |48, spring retainer |5I, spring 2,and longitudinally split inner casing |52 are freed from the apparatusand provide a means of freeing the parachute for deceleration of theapparatus before it strikes the water surface.

The function of counterweight I|0 is to position the center of gravityof the apparatus properly for free falling attitude as shown in C ofFig. 4. When the parachute is inflated as shown in B, Fig. 4, thecounterweight ||0 is caused to separate from bulkhead by inertiareaction. Counterweight I|0 is "secured to bulkhead by an adjustablemeans so that the magnitude of force required to remove it from bulkheadmay be varied. Stud |06 is securely attached to bulkhead I II by screw|05. Ball |01 is retained against the circular V notch of stud |06 bymeans of spring |08 exerting a pressure proportional to the adjustmentof screw |09. Ball |01, spring |08 and screw |09 are retained within acavity within counterweight I I0. When the actual weight ofcounterweight ||0 is increased to a larger apparent weight due todeceleration in the 5 roper direction, ball |01 is forced against spring09 by the inclined plane of stud |06 due to ounterweight I I separatingfrom bulkhead Yhen the apparent weight of counterweight ecomes sumcientto cause ball |01 to overcome r'essure of spring |08, ball |01 moves adistance uiilcient to clear the large diameter oi' stud |06 ndcounterweight I I I carrying with it screw |09. bring |03-and ball |01separates and becomes ree of bulkhead III. Several assemblies of crew|05, stud |06, ball |01, spring |08 and crew |09 are required and arespaced equidisantly in a circular manner.

The election of Fig. 3 from Fig. 2 causes safety witch 2, which iselectrically connected in series rith a time delay position operatedswitch (to e later herein described in detail), to close and onnect abattery source of E. M. F. to the time elay position operated switch.

Referring to Fig. 2, safety switch -2 shown in etail in Fig. is securelyattached between ring B-and bulkhead 29. Ring 28 is securely attached obulkhead 29. Lanyard |3| is securely attached etween iin band |53 andkeeper |36. Safety crews I3 and |31 securely attach, and keep inngagement, keeper |36 to switch body |33 and rovide a means ofpreventing safety switch -2 rom closing the circuit in which it isconnected rom any accidental cause previous to launching he apparatus.Safety screws ||3 and |31 are manually removed from switch body |33immeiatelyprior to launching the invention. When ig. 3 is ejected fromFig. 2 during flight through he atmosphere, lanyard |3| removes keeper|36 rom shaft I4, thus permitting shaft H4 to move rito switch block |33due to pressure exerted by ompression spring H5 which is securely heldetween switch body |33 and support H6. Suport I|6 is securely attachedto shaft lid. Elecrical insulator stud securely attaches elecricalcontact sleeve lla and electrical insulator ollar I|1 to shaft H4. ShaftH3 moves into witch block |33 until fiemble washer |38, secured nposition by means of support plate |39 and nut 40, both of which aresecurely attached to shaft I4, is held in a liquid pressure tight manner`gainst the exterior surface of switch block |33. llectrical contactsleeve IIB then forms an elecrical contactv and closes the circuitbetween pring contacts I9 and |29. Spring contact suplort is securelyattached to switch block |33 n a liquid pressure tight manner. Springconacts ||9 and |29 are securely attached to spring ontact support |25by means of rivet |2I. Elecrical insulating washers |22, |23, '|21 and|28 nsulate spring contacts ||9 and |29 from spring ontact support |25and rivet |2|. Rivet |2| is lectrically insulated from spring contactsuport |25 by means not shown. Spring contacts i9 and |29 are connectedinto the circuit to be losed by lead wires |24 and |25 which are seurelyelectrically attached ,to spring contacts i9 and |29 and are secured inspring contact upport I 25 in a liquid pressure tight manner. Ioles and|32 are for the purpose of securing witch block |33 in position betweenring 23 and ulkhead 29 by means not shown.

Ring 33 is securely attached to cap 3| which s securely attached tocartridge adapter 4|. Cap 1| and cartridge adapter 4| retain cartridgesuport plate 32 in a secure and pressure-tight manler. Gasket 34 servesas a water and gas pressure eal. Cartridge support plate 32 securelyretains electrical insulator 35 within which cartridge llectrode 39 issecurely attached. Cartridge electrode 39 makes electrical contact withcartridge 40 with one of its ends while attached to its other end isinsulated electrical conductor 36. Cartridge adapter 4| is securelyattached to support 5 tube 63 in a water and gas pressure-tight mannerand securely retains gasket 41, gasket 46, gasket 45, orifice plate 44,and antenna lock-release body 52 in fixed positions. Orifice port 42within orice plate 44 is adjustable for the purpose of bleeding gaspressure as required. The telescopic antenna is secured in a collapsedposition by means of flexible cable 58 which is attached to piston 53and securely attached to the smallest section of the antenna, antennasection 12. Collar 51 prevents damage to iiexible cable 58. The lengthof iiexible cable 58, shown as 59, and ex ternal to piston 53, is oflarger diameter than the remainder of flexible cable 58. The battery forthe radio, both not shown since they may be of a variety of forms, isretained between bulkhead 29 and support disc 16 by means of coupling18. Opening 11 in support disc 16 allows Wires to pass from battery toradio. One support plate oi the radio chassis, not shown, is securedbetween support disc 16 and coupling 18. Support tube 63 is securelyconnected in a gas pressure-tight manner to support tube 19 by means ofcoupling 18. Tube 63 is of larger inside diameter than tube 19 so thatantenna locking spring 62 is free to expand and is not obstructed in anymanner when the antenna is being erected to its outstretched length.Coupling 80 is connected in a gas pressure-tight manner to tube 19 andis constructed of a radio frequency insulating material. Attached in asecure and gas pressure-tight manner to coupling 30 is a radio switchcomposed of elements 89, 81, 63, 85, 90, 9|, 92, |58, 86, 83, 93,

94, 95 and 84, which will be described later. Oriice 62 within coupling80 is for the purpose of bleeding the proper gas pressure to the radioswitch to cause it ,to operate in a satisfactoryl manner.

Metallic coupling |56 is securely attached to insulating coupling 60 ina gas pressure-tight manner and performs the following functions:

to conduct radio frequency current into the antenna locking spring 62shown dotted in its position after antenna erection; and to form acircular restricting cavity above shoulder 8| of coupling 60 of largerdiameter than inside diameter of coupling 80 and having shoulder |55 ofsmaller diameter than outside diameter of antenna piston 60, so thatwhen antenna piston is moving at high velocity due to gas pressureexerted on its 55 face it will be prevented from moving further thanshoulder |55 by interference of piston 60 with shoulder |55, and at thesame time, antenna locking spring 62 expands within the restrictingcavity, thus permanently preventing antenna 50 piston 60 from moving dueto vibration, without the space bounded by shoulders 8| and l 55.Connection of radio frequency current to coupling |56 is not shown sinceit may be accomplished by ordinary means.

'Ilbe 96 is securely attached to coupling |56 in a gas pressure-tightmanner and provides a guide tube for the antenna during erection and asupport after erection. Lock collar 91 is adjustable on tube 96 for thepurpose of reinforcing insulating collar 98. Insulatingcollar 99insulates tube 96 from bulkhead and is retained in position byadjustable collar |02 which is attached to tube 96. Gaskets |00 and |0|are securely held in position and are water pressuretight. Sealingdiaphragm |04 is securely held in position against tube 96 by adjustablecollar |03 which is securely attached to adjustable collar |52.Diaphragm |84 is secured in a water pressuretight manner and is of suchmechanical strength that it will withstand the plunging of the inventioninto water at high velocity without breaking or leaking and yet can bepunctured by antenna sections 68, 61, 66, 65 and 64 when gas pressure isapplied to erect the antenna. The sealing diaphragm |84 causes awater-tight seal to be made around antenna piston 69 and tube 96 uponcomplete erection of the antenna, thus preventing water leakage intotube 96 that may be caused by Waves breaking over the top of the device.

Bulkhead 29 is securely attached in a water pressure-tight manner totube 63 by means not shown. Shield can or outer housing II2 is securelyheld in positiony in a water pressure-tight manner between bulkheads 29and III. Bulkhead I I is securely held in position by adjustable collarII|2 which is adiustably attached to tube 96, thereby holding insulator99 in position so that bulkhead III is retained securely betweeninsulator 99 and insulator 98 with insulator 98 being secured inposition by adjustable collar 91 which is adjustably attached to tube96.

Support ring 28 is securely attached to bulkhead 29. Battery 14 issecured in battery cup 30 and made water pressure-tight by sealingcompounds 13 and 15. Several battery cups are shown which are securelyattached to support ring 28. Mercury switch cap 26 is`securely attachedto support ring 28 by screw 21. Safety switch -2 is securely held inposition between support ring 28 and bulkhead 29 by means not shown.Batteries 14 are connected with mercury switch lead wires I and 6,safety switch lead wires I 24 and |26 and cartridge lead wire 36 andcartridge adapter 4| to form a firing circuit for cartridge 40.Cartridge adapter 4I is at ground potential.

'I'he tubular telescopic antenna may be composed of any Anumber oftelescopic tubes. The antenna of this invention is composed oftelescopic tubes 68, 61, 66, 65 and 64, each of which has securelyattached to one end its respective piston, namely pistons 12, 1I, 10, 69and 60. 'I'he ends of telescopic antenna sections, opposite to the ends,to which the pistons are securely attached, are formed to a smallerdiameter for a short longitudinal length as shown on collapsed antennaItelescopic tubes 61, 66, 65 and 64. Telescopic tube 68 is the innermosttube and is of uniform diameter. Pistons 12, 1|, 10 and 69 have a taperon the outside diameter for the purpose of providing a gas pressure sealagainst the inner surface of telescopic antenna tubes 61, 66, 65 and 64respectively, and also for the purpose of mating with the smaller insidediameters of the ends 61, 66, 65 and 64 so that the antenna is securelyelectrically and mechanically locked after gas pressure is applied.Pistons 60, 69, and 1I pass expanding gas from one to the other andfinally to piston 12 by means of a concentric hole or port continuingtheir full length, except piston 12, which has no hole. The holes orports in the several pistons serve the added function of permittingfiexible cable 58 which is securely attached to piston 12 topass throughuntil it is nally attached to release piston 53. The function offlexible cable 58 is to cause the telescopic antenna to remain in acollapsed position during handling and free-flight of the device anduntil gas pressure is created by firing of cartridge 48. Piston 60 is ofdifferent construction than the other pistons having uniform outsidediameter with a circular groove |54 which retains a spring 82 in such amanner that, when the antenna is in its erected position as shown bydotted lines, spring 62 engages both piston 60 and shoulder 8| ofinsulated coupling 80 to prevent movement of piston from without thecavity in coupling |56, said cavity bounded by shoulders 8| and |55.Spring 62 is always in contact with the metallic surface of metalliccoupling |56 and conducts radio frequency current from coupling |56 topiston 60 which conducts current to telescopic tubes 64, etc. to thecomplete antenna. Flexible cable 58 passes through all pistons andtelescopic antenna tubes upon antenna erection except tube 68 andremains securely attached by one end to piston 12.

Cartridge 40 is red by the firing circuit after the apparatus hasalighted upon the water, inverted its position, and the expiration of atime delay caused by a time delay position operated switch to be laterdescribed.

The following gives a more detailed description of the time delayposition operated switch.

Referring to Fig. 2, the mercury switch, which may also utilize othersuitable electrolytes, is composed of a housing formed by cap 26, bodyI4 and cap 9. Cap 26, body I4 and cap 9 are constructed of a materialwhich will not cause amalgamation with mercury and which is anelectrlca1 non-conductor. Cap 26 is securely attached to support ring28. Body I4 is securely attached in a water pressure-tight manner to cap26 with gasket 25 as a mercury and water seal. Cap 9 is securelyattached to body I4 in a water pressure-tight manner with gasket I0serving as a mercury and water seal.

Cavities 24, 23, 22, 2| and 20 contain mercury which is retained inthese cavities by flexible Washer I9 being retained tightly againstshoulder |59. Flexible washer I9 is securely retained between supportsI1 and I8. Support I1 is securely attached to shaft 5, thus securingsupport I8 to shaft 5. Flexible washer I6 is secured to shaft 5 by meansof support I8. Shaft 5 passes freely through a centrally located hole incap 9.

Cap 3 is securely attached to shaft 5 and retains spring 4 betweenitself and cap 9. Spring 2 freely fits around a shoulder of cap 3 andoverpowers spring 4 when compressed suiliciently. It is thus seen that,when spring 2 is compressed sufiiciently by Fig. 3 being properlyattached to bulkhead 29 of Fig. 2, the flexible washer I9 seals cavityI5 from cavities 24, 23, 22 and 2|, thereby preventing mercury fromleaving cavities 24, 23, 22

and 2| and entering cavity I5, irrespective of the position of theinvention. Spring 2 also serves as a means of adjustment for variationin dimensions of manufactured parts.

Electrical contact I3 is securely attached to cap 9 and is electricallyconnected to electric conducting lead wire 6. Electric insulating washerI2 is securely attached to cap 9. Electrical contact II is securelyattached to cap 9 and is electrically connected to electric conductinglead wire I. Lead Wires I and 6 are coated with a waterproof materialand are made watertight at their entrance and passage through cap 9 bymeans of counterbore 1 being lled with a durable plastic waterproofcompound.

When Fig. 3 is ejected from bulkhead 29 of Fig. 2, spring 2 is releasedwhich allows spring 4 to extend and move flexible washer I9 away fromshoulder |59. Shaft 5 carrying flexible washer I6 moves to its otherextreme position and causes flexible washer I6 to be iorcedagainstshoulder 43 of cap 9 in a'water pressure-tight manner. By virtue of theFig. 2 dropping to a surface of the earth on a parachute attached toring 33, mercury is restrained by gravity from entering cavity I5.

Upon inversion of Fig.2 so. that cavities 24, 23, 22 and 2l are at ahigher elevation than cavity I5, mercury is caused by gravity to entercavity I5. The distance between the inside surface of cap 26 and theclosest end of the material surrounding cavity 23 is such that themercury in cavity 23 will readily ow into cavity I5, thereby clearingcavity 23 so that it then becomes an air relief for cavity I by passingair from cavity I5 into cavity 24 as said air is displaced Aby mercuryflowing through port 2i. By virtue of cavity 23, the air pressureswithin cavities 24 and I5 are equalized and prevent formation of an airlock. Various relationships between the sizes of cavities 23, 24, 22,port 2l and cavity I5 may be determined which will cause various timedelays. Cavity 22 reduces the length of port 2I for the purpose ofreducing friction loss when mercury is passing through port 2l andthereby permitting the wall between cavities 24 and I5 to be of a sizesufficient to withstand all shock loading incident to the properoperation of the invention of Fig. 1.

The volume of cavity I5 in conjunction with Volumes of cavities 24, 23,22 and the volume of the annular space adjacent to electrical contactrings I3 and II and inside diameter of body I4, is determined in such amanner that positive electrical contact between rings I3 and II resultsfor a suiiicient given volume of mercury within cavity I5. 'Ihisparticular arrangement insures positive operation of the mercury switchwhen cavity 24 is at higher elevation than cavity I5 irrespective ofposition with respect to a vertical axis.

The following gives a more detailed description of the antenna lock andrelease cylinder.

Referring to 1, the telescoping antenna represented by telescopic tubes68, 6l, 66, 65 and 64 is held in a restrained collapsed position byflexible cable 58 which is securely attached to piston 'I2 (which is inturn securely attached to telescopic tube 68) and removably attached topiston 53 of the device. Flexible cable 58 is of uniform diameter exceptthat the portion shown as 59 is of larger diameter so that it isrestrained by a slot cut in the rod end of piston 53 of the device.

When cartridge 40 is ignited, gas is permitted to bleed through orifice42 of orifice plate 44 and thence through port 48 of the device to theface of piston 53 which heretofore has been restrained in the positionshown by lock pin 5I which is spring loaded by spring 50, all held inposition by adjustable screw 49. Gas pressure is exerted upon piston 53and causes it to move in a direction which completely disengagesiiexible cable 58 before piston 53 uncovers any portion of port 56 ofthe device. When port 56 is uncovered by piston 53 the gas passesthrough port 56 and expands against antenna pistons 68, 69, 18, II and12, thus causing erection of the antenna. Port 56 is a relief port torelieve any back pressure. Body 52 carries all the parts necessary tothe device and transmits all inertia reaction weight of the antenna,upon deceleration due to parachute opening, to tube 63 thence throughcartridge adapter 4I to cap 3| and nally to ring 33. Plug screw 55 isrequired for assembly purposes. Piston 53 is restrained from anychattering action during gas expansion by locking pin 5I` engaging thestepped portion of piston 53.

Cri

The following gives a more detailed description of the pressure operatedelectric switch.

Referring to Fig. 1, switch body 88 is securely attached in a gaspressure-tight manner to insulated coupling 88. When plug 68 of thetelescopic antenna is approaching its erected position shown in dottedlines,it allows gas pressure to bleed through port 82 of insulatedcoupling 88. Gas pressure then is applied through port 89 to piston 86thus causing piston 86 to move in such a position that its smallestmeter end exerts suiiicient pressure against elec rical spring contacts93, 94 and 95 to cause electrical connection to be made between springcontacts 93, 94 and 95. Many other arrangements of spring contacts willbe apparent. Insulating spacers 96, 9I and 92 electrically insulatespring contacts 83, 94 and 95 from each other and switch body 88 priorto closing of the spring contacts 93, 94 and 95. No connection of switchcontacts 93, 94 and 95 to an external circuit has been shown since thismay be of various forms. Locking pin locks piston 86 in position bothbefore and after application of the operating gas pressure. When piston86 has been acted upon by gas pressure, locking pin 85 is caused torecede against spring 84 by force transmitted to it from the taperedsurface of piston 86. Spring 84 causes locking`pin 85 to move beyond thelarge diameter end of piston 86 after the large diameter end of piston85 has been moved by gas pressure to such a position that the springcontacts 93, 94 and 95 are closed. Piston shoulder I58 preventsovertravel of piston 86 and thus protects the spring contacts from beingdistorted. Screw 83 retains spring 84 in position. Cap 81 permitsassembly of piston 86 and retains piston 86 in position during vibrationand shock loading when the parachute opens and when the device of Fig. 2strikes the surface of the earth so that no load is imposed upon lockpin 85.

The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

What is claimed is:

1. In a radio drift bomb to be dropped from an aircraft for the purposeof obtaining the drift angle of said aircraft, comprising: a rst casing;a radio transmitting apparatus and a source of power therefor housed insaid first casing; a second casing having air vane means thereon and aparachute housed therein for controlling the rate of descent of saidf'lrst casing; means for detachably securing said second casing to saidrst casing; means for disengaging said second casing from said rstcasing after the said drift bomb has fallen a predetermined distance, sothat said second casing may fall freely of said first casing therebyreleasing said parachute; a counterweight for orienting the drift bombfor desirable parachute opening; and means for detachably securing saidcounterweight to said first casing and operative for releasing saidcounterweight by inertia reaction resulting from the opening of saidparachute, said counterweight being disposed and of a mass operative tochange the center of gravity and center of buoyancy of said drift bomb.whereby said bomb, upon alighting on a water surface, assumes a positiongenerally inverted with respect to that which it had while fallingfreely through atmosphere.

2. The apparatusl dened in claim 1 characterized further by the additionthereto of a source l1 of fluid pressure mounted on said ilrst casing; atelescopic antenna mounted on said first casing. adapted to be erecteddirectly by said iluid pressure; and means for conducting radio signalsfrom said transmitter to said antenna.

3. The apparatus deilned in claim 1 characterized further by theaddition thereto of electrically controlled gas pressure providing meansmounted on said nrst casing: a telescopic antenna mounted on said nrstcasing, adapted to be erected by said gas pressure source; means forconducting radio signals from said transmitter to said antenna; andposition-operated switch means mounted on said ilrst casing forcontrolling the initiation of operation of said gas pressure providingmeans adapted to eii'ect a closed circuit when the first casing assumesan inverted position in water. said electrically controlled gas pressureproviding means and said position operated switch means being connectedin series across said power supply.

4. The apparatus defined in claim 1 characterized further by theaddition thereto of electrically controlled gas pressure providing meansmounted on said ilrst casing; a telescopic antenna mounted on said iirstcasing, adapted to be erected by said gas pressure source; means forconducting radio signals from said transmitter to said antenna; a gaspressure operated electric switch mounted on said iirst casing, adaptedto be operated by said gas pressure source, for initiating the operationof said transmitter; and position operated electrolytic switch meansmounted on said iirst casing for controlling the initiation of operationof said gas pressure providing means, adapted to be inoperative whensaid first and second casings are in engagement. operative when saidsecond casing is moved out of engagement with said first casing. andadapted to effect a closed circuit when the iirst casing assumes aninverted position in water, said electrically controlled gas pressureproviding means and said position operated switch means being connectedin series across said power supply.

5. 'Ihe apparatus defined in claim 1 characterized further by theaddition thereto of electrically controlled gas pressure providing meansmounted on said iirst casing; a telescopic antenna mounted on said iirstcasing, adapted to be erected by said gas pressure source; means forconducting radio signals from said transmitter to said antenna; safetyswitch means mounted in said rst casing adapted to be p0- sitioned intoconductive engagement for armed operation when said second casing iscaused out of engagement with said first casing; and position operatedelectrolytic switch means mounton said rst casing for controlling theinitiation -of operation of said gas pressure providing means, adaptedto be inoperative when said rst and second casings are in engagement,operative when said second casing is moved out of engagement with saidilrst casing, and adapted to effect a closed circuit when the ilrstcasing assumes an inverted position in water, said electricallycontrolled gas pressure providing means, said position operated switchmeans, and said safety switch means being connected in series acrosssaid power supply.

6. The apparatus dened in claim 1 characterized further by the additionthereto of electrically controlled gas pressure providing means mountedon said nrst casing; a telescopic antenna mounted on said iirst casing,adapted to be erected by said gas pressure source; means for 12conducting radio signals from said transmitter to said antenna; meansmounted in said first casing normally holding said antenna in acollapsed position and adapted to be released by said gas pressuresource; a gas pressure operated' electric switch mounted on said iirstcasing. adapted to be operated by said gas pressure source, forinitiating the operation of said transmitter; safety switch meansmounted on said first casing adapted to be positioned into conductiveengagement for armed operation when said second casing is moved out ofengagement with said ilrst casing; and position operated electrolyticswitch means mounted on said rst casing for controlling the initiationof operation of said gas pressure providing means, adapted to beinoperative when said nrst and second casings are in engagement,operative when said second casing is moved out of engagement with saidfirst casing, and adapted to effect a closed circuit when the firstcasing assumes an inverted position in water, said electricallycontrolled gas pressure providing means. said safety switch means, andsaid position operated switch means, being connected in series acro saidpower source.

7. The apparatus defined in claim 1 characterized further by theaddition thereto of an electrically controlled gas pressure producingcartridge mounted on said first casing; a telescopic antenna mounted onsaid first casing, adapted to be erected by said gas pressure source;means for conducting radio signals from said transmitter to saidantenna; means mounted on said iirst casing normally holding saidantenna in a collapsed position and adapted to be released by said gaspressure source; a gas pressure operated electric .switch mounted insaid first casing, adapted to be operated by said gas pressure source.for initiating the operation of said transmitter; safety switch meansmounted in said ilrst casing adapted to be positioned into conductiveengagement for armed operation when said second casing is forced out ofengagement with said rst casing; time delay position operatedelectrolytic switch means mounted on said iirst casing for controllingthe initiation of operation of said gas pressure providing means,adapted to be inoperative when said ilrst and second casings are inengagement, operative when said second casing is forced out ofengagement with said rst casing, and adapted to eii'ect .a closedcircuit when the iirst casing assumes an inverted position in water; asecond source of electrical power mounted on said first casing connectedin series with said electrically controlled gas pressure producingcartridge, said safety switch means, and said time delay positionoperated electrolytic switch means; and a frangible cover securedwatertight over the outlet opening of said tube which can be broken bythe antenna as it is forced into erection through the tube outlet.

8. In a radio drift bomb adapted to be dropped from an aircraft for thepurpose of obtaining the drift angie of said aircraft, comprising: a rstcasing having a tube carried thereby containing a telescopic antenna'adapted to be erected by gas pressure; a radio transmitting apparatusand a source of power therefor housed in said rst casing, saidtransmitter Vbeing electrically connected to said antenna; a secondcasing having air vane means thereon and a parachute housed therein forcontrolling the rate oi descent of said first casing. said sec- 'audace'13 ond casing being detaenabiy secured to sala erst casing; means forforcing said second casing opening; and means for detachably securing.said counterweight to said rst casing and operative for releasing Asaidcounterweight by in- -ertia reaction resultingfrom the opening of saidparachute, said counterweight being disposed and of a mass operative tochange the center of gravity and center of buoyancy of said drift bomb,whereby said bomb, upon alighting on a water surface, assumes a positiongenerally linvertedvwith respect to that which it had while fallingfreely through the atmosphere.

9. In a radio drift bomb adapted to be dropped from an aircraft for thepurpose of obtaining the drift angle of said aircraft, comprislng: afirst casing having a tube mounted longitudinally therein containing atelescopic antenna adapted to be erected by gas pressure; a radiotransmitting apparatus and a first source of power therefor housed insaid ilrst casing, said transmitter being electrically connected to saidantenna; a second casing having air vane means thereon and a parachutehoused therein for controlling the rate of descent of said first casing,said second casing being detachablysecured to said iii-st casing; meansfor disengaging said second casing from said rst casing after the saiddrift bomb has fallen a predetermined distance, so that said secondcasing may fall freely `of said iirst casing thereby releasing saidparachute; a counterweight for orienting the drift bomb for desirableparachute opening; means for detachably securing said counterweight tosaid rst casing and operative for releasing said\ counterweight byinertia reaction resulting from the opening of said parachute, saidcounterweight being disposed and of a mass operative to change thecenter of gravity and center of buoyancy of said drift bomb, wherebysaid bomb, upon alighting on a water surface, assumes a positiongenerally inverted with respect to that which it had while fallingfreely through the atmosphere; and a frangible cover secured Watertightover the outlet opening of saidtube which can be broken by the antennaas it is forced into erection through the tube outlet.

10. The apparatus defined in claim 9 characterized further by theaddition thereto of a source of gas pressure mounted on said firstcasing for erecting said antenna.

11. The apparatus dened in claim 9 characterized further by the additionthereto of electrically controlled gas pressure providing means mountedon said mst casing for erecting said antenna; and position operatedswitch means mounted on said first casing for controlling the initiationof operation of said gas pressure providing means adapted to effect aclosed circuit when the iirst casing assumes an inverted position inwater, said electrically controlled gas pressure providing means, andsaid position operated switch means being connected in series acrosssaid power source.

l2. The apparatus deiined in claim 9 characterized further by theaddition thereto of electrically controlled gas pressure providing meansmounted on said first casing for erecting said antenna; a gas pressureoperated electric switch mounted on said iirst casing, adapted to b'e'operated by said gas pressure source. for initiating the operation ofsaid transmitter; and position operated electrolytic switch meansmounted on said first casing for controlling the initiation of operationof said gas pressure providing means, 'adapted to be inoperative whensaid iirst and second casings are in engagement, operative when saidsecond casing is moved out of engagement with said rst casing, andadapted to effect a closed circuit when the first lcasing assumes aninverted position in Water, said electrically controlled. gas pressureproviding means, and said position operated switch means being connectedin series across said power source.

13. The apparatus dened in claim 9 characterized further by the additionthereto of electrically controlled gas pressure providing means mountedon said first casing for erecting said antenna; safety switch meansmounted on said first casing adapted to be positioned into conductiveengagement for armed operation when said second casing is caused out ofengagement with said lrst casing; and position operated electrolyticswitch means mounted on said iirst casing for controlling the initiationof operation of said gas pressure providing means, adapted to beinoperative when said rst and second casings are in engagement,operative when said second casing is moved out of engagement with saidiirst casing, and adapted to eiect a closed circuit when the rst casingassumes an inverted position in water, said electrically controlled gaspressure Vproviding means, said safety switch means, and said positionoperated switch means being connected in series across said powersource.

14. The apparatus defined in claim 9 characterized further by theaddition thereto of electrically controlled gas pressure providing meansmounted on said first casing for erecting said antenna; a gas pressureoperated electric switch mounted on said Virst casing, adapted to beoperated by said gas pressure source, for initiating the operation ofsaid transmitter; safety switch means mounted on said first casingadapted to be positioned into conductive engagement for armed operationwhen said second casing is moved out of engagement with said iirstcasing; and position operated electrolytic switch means mounted on saidrst casing for controlling the f initiation of operation of said gaspressure providing means, adapted to be inoperative when` said first andsecond casings are in engagement, operative when said second casing ismoved out of engagement with said first casing, and adapted to effect aclosed circuit when the first cas-- ing assumes an inverted position inWater, said electrically controlled gas pressure providing means, saidsafety switch means, and said position operated switch means beingconnected in series across said power source.

15. The apparatus dened in claim 9 characterized further by the additionthereto of an electrically controlled gas pressure producing cartridgemounted on said rst casing for erecting said antenna; means mounted onsaid first casing normally holding said antenna in a collapsed positionand adapted to be released'by said gas pressure source; a gas pressureoperated electric switch mounted on said first casing, adapted to beoperated by said gas pressure source, for initiating the operationofvsaid transmitter; safety switch means mounted on said first casingadapted to be positioned into conductive enfirst casing. and adapted toeffect a closed circuit when the rst casing assumes an inverted positionin water; a second source of electrical power mounted on said rst casingconnected in series wtih said electrically controlled gas pressureproducing cartridge, said safety switch meansfand said time delayposition operated electrolytic `switch means.

RAYMOND L. FREAS.

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